Liquid crystal display devices utilize a liquid crystal composition for display. A typical display method thereof is applying voltage to the liquid crystal composition sealed between paired substrates to change the alignment state of the liquid crystal molecules in the liquid crystal composition according to the applied voltage, thereby controlling the amount of light transmission. These liquid crystal display devices having characteristics such as thin profile, light weight, and low power consumption have been used in a broad range of fields.
The alignment of liquid crystal molecules with no voltage applied is typically controlled by alignment films having been subjected to an alignment treatment. Although rubbing has been a widely used alignment treatment method, photo-alignment methods allowing non-contact alignment treatment have now been studied and developed. Known various photo-alignment methods include photodecomposition, photo-isomerization, and photo-dimerization.
Developed photo-alignment methods include those using a photo-alignment film with an acrylic backbone as the main chain and a photo-functional group such as a cinnamate group in a side chain (for example, Patent Literature 1 and Non Patent Literature 1).